OsbZIP72 Is Involved in Transcriptional Gene-Regulation Pathway of Abscisic Acid Signal Transduction by Activating Rice High-Affinity Potassium Transporter OsHKT1;1

Abstract

We created CRISPR-Cas9 knock-out and overexpressing OsbZIP72 transgenic rice plants to gain a better understanding of the role and molecular mechanism of OsbZIP72 gene in stress tolerance, which has remained largely elusive. OsbZIP72 was expressed and integrated into rice transgenic plant genomes, and the OsbZIP72 transcript in overexpression lines was elicited by salinity, abscisic acid (ABA) and drought stresses. OsbZIP72 overexpressing plants showed higher tolerance to drought and salinity stresses, while knock-out transgenic lines showed higher sensitivity to these stresses. The differentially expressed genes (DEGs) from RNA-sequencing data encompassed several abiotic stress genes, and the functional classification of these DEGs demonstrated the robust transcriptome diversity in OsbZIP72. Yeast one-hybrid, along with luciferase assay, indicated that OsbZIP72 acted as a transcriptional initiator. Remarkably, electrophoresis mobility assay revealed that OsbZIP72 bound directly to the ABA- responsive element in the OsHKT1;1 promoter region and activated its transcription. Overall, our findings revealed that OsbZIP72 can act as a transcriptional modulator with the ability to induce the expression of OsHKT1;1 in response to environmental stress through an ABA-dependent regulatory pathway, indicating that OsbZIP72 can play a crucial role in the ABA-mediated salt and drought tolerance pathway in rice.